VINCENT C. Gray (D) is weighing whether to run next year for reelection as D.C. mayor. Under normal circumstances, it would be assumed that a mayor with solid accomplishments in his first term would seek four more years in office. The circumstances, though, are anything but normal, given an ongoing investigation by the U.S. attorney, the criminal convictions of close Gray allies and continuing ethical questions about his 2010 campaign.

Mr. Gray should take serious pause. It should be self-evident that, before he can ask residents of this city for a second term, he must be forthright about the circumstances of the campaign that got him into office, one that federal prosecutors say was compromised by backroom deals and corrupted with illegal cash.

Petitions to get on the ballot for the April 1 primary will become available Nov. 8 and must be returned with the signatures of 2,000 registered voters by Jan. 2. “We are going to get to a decision within the next few weeks,” Mr. Gray told WAMU-FM’s “The Politics Hour” last week. He drew a distinction between the problems of his 2010 campaign and the accomplishments of his administration. “It’s very unfortunate things happened during that campaign,” he said, “but they did happen during the campaign and not during this administration’s work on behalf of the people of the city.”

Mr. Gray’s accomplishments are real: smart cabinet appointments, unwavering support for school reform, strong leadership during the federal government shutdown and more. But concerns about how he got into office cannot so easily be dismissed.

The federal probe into Mr. Gray’s campaign has its roots in the appointment of Sulaimon Brown to a high-paying city job shortly after Mr. Gray took office. Dismissed after controversy arose about his employment, Mr. Brown, a fringe mayoral candidate in 2010, went public with allegations that he was promised a D.C. government job and given cash by the campaign in exchange for attacking then-Mayor Adrian M. Fenty in the Democratic primary.

“Was there a quid pro quo here? Did we ask him to do something on behalf of my candidacy, and did we give him something? The answer is unequivocally no,” Mr. Gray told The Post in March 2011.

A year later, in May 2012, Thomas Gore, a key finance official in Mr. Gray’s campaign and longtime confidant, pleaded guilty to charges that he made illegal contributions to Mr. Brown and destroyed records documenting the payoffs; Howard Brooks, consultant to the Gray campaign, pleaded guilty to charges he lied to investigators about payments to Mr. Brown. Two months later, U.S. Attorney Ronald C. Machen Jr. revealed that a “sinister” shadow campaign, fueled by $653,800 in illegal contributions from a prominent businessman with city contracts, had operated in tandem with Mr. Gray’s official campaign. Jeanne Clarke Harris and Vernon Hawkins, friends of the mayor, have both pleaded guilty to federal charges.

Federal prosecutors give no clue as to when they will wrap up their investigation; an appeal to the U.S. Supreme Court by Jeffrey E. Thompson, who allegedly underwrote the shadow campaign, on a related matter could add further delay. Mr. Gray has declined requests to meet with investigators and — aside from general denials of wrongdoing — has refused to publicly discuss any details of his campaign.

Before Mr. Gray thinks about mounting a second mayoral campaign, he needs to answer the questions that linger over his first.